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JavaScript□□□□□□□(□□)4DDJavaScriptDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDvarDDDDDDDDDDDDDDDDQvarQDDDDDDDDDDDQ1DDDDDDDDDDJavaScriptvarglobal=""Global"";test;functiontest{varlocal=""Local";document.writeln(global);document.writeln(local);}document.writeln(global);document.writeln(local);2DDDDDDCookieiDDDDcookieDDDDDDDDDDDDDDiiDDDcookieDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDcookieQDDDQ3QQJavaScriptQDDDQfunctionUUUUUNultypeofDDDDDDDDDDDDDDDnullDDDDDDDDDDD5QQundefined^boolean^numberQBooleanQDDDDDDDDtrueQfalseQ5QFunctionDDQJavaScriptDDDDFunction叮叮□叮叮DQDQFunctionQDDDDQFunctionQDDDDDQDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD6DQDDDQargumentsQJavaScriptDDDDDDDDDDDDDDQargumentsDQDDDDDDDDDDDQarguments.lengthDDDDDDDDDDDDDD7DDQQ.lengthDDDDDDDDDDDlengthDDDDDDDDDDDDDDDDDDDDDDDargumentsQQQarguments.lengthDDDDDDDDDDDDDD8QJavaScriptQDDDDDDDDQUndefined^NullQBoolean^NumberQQStringQQQQQQJavaScriptUUUUcharQDDDQUndefinedDDDDDDDDDDDundefined^9QtypeofDDDDDDDDDstringQQobjectD10DDJavaScriptDDDDDDDDDDDDDDDtypeofDDDDDDDDDDDDDDDDDDDDDDDDDD5QQundefined^boolean^numberQDQDQundefinedllDnullQundefinedQQQundefinedQDDDQnullQDDDDDDDQnullQundefinedQQQJavaScriptalert(undefined==null);//QDDDQtrue11DDDDDDDQJavaScriptQQ3QDDDDDDQBooleanQvalueQQNumberQvalueQQStringQvalueQQ12DObjectUUQJavaScriptQDDDDDDDQObjectQDDDQODDObjectQQJavaScriptvarobject二newObject;for(varvinobject){alert(v);}DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDfalseQQQQObjectQQDDDDDDDDDDDObject叮叮叮叮叮叮JavaScriptalert(object.propertyIsEnumerable("prototype"));DDDDDfalseDDDDDDDObjectDDDDDDDDDDDDDQDDDDDDQwindowQDDDDDDDDDDQDwindowQDDDDDDDDDDQJavaScriptfor(varvinwindow){console.log(v);}DChromeDDDDDDDDDDDDDDDDDDDDDDDDDDDDDwindowDDDDDDDDDDDDD13DDJavaScriptDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD/DDDDDDDJavaScriptvarobject二newObject;alert(object.username);//undefinedODobject.username=""zhangsan";alert(object.username);//zhangsanobject[""password""]=""123";alert(object.password);//123deleteobject.username;//血usernameDQDQalert(object.username);14QJavaScriptQDDDDDDDDDQDDDDDDDDDDJavaScriptvarobject二{username:zhangsan,password:12345};alert(object.username);alert(object.password);15DDDDDDDJavaScript//ODDvararray=newArray;array.push(l);array.push(2);array.push(3);alert(array.length);//DDDDDDDvararray=[1,25,4];array.sort;alert(array);DDDDDsortUUUU叮叮叮1D25D4DDDDDDDDDDDDDQQJavaScriptQQQsortDDDDDDDDDDDDDDDDDDDDDDDDtoStringDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDODDDDDDJavaScriptfunctionpare(num1,num2){vartemp1=parseInt(num1);vartemp2=parseInt(num2);if(temp1return-1;}elseif(temp1==temp2){return0;}else{return1;}}vararray=[1,25,3];array.sort(pare);alert(array);DDDDDDDDDDDDDDDDDDDDJavaScriptvararray=[1,25,3];array.sortfunction(num1,num2){vartemp1=parseInt(num1);vartemp2=parseInt(num2);if(temp1return-1;}elseif(temp1==temp2){return0;}else{return1;}});alert(array);16QJavaScriptQDDDDQ5DDDDJavaScriptnamDDDDDDDDDDDDDiDDDDDDDDDDDDODDDDDDDDDDDDDDDDJavaScriptvarobject二newObject;//QQnameQQobject.name=""zhangsan";//QQsayNameQQobject.sayName=function(name){this.name=name;alert(this.name);};object.sayName(〃kyle"");//DDsayNameQQQDDDDDDkyleDDDDDDDkyleDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDiiDDDDDDDDDDDDDDDDDDDJavaScript//DDDDfunctioncreateObject{varobject二newObject;//□□□血object.name=""zhangsan";//QDDDDDDQnameQQobject.password=""123";//QDDDDDDQpasswordQQobject.ge...